Wordnet 3.0
NOUN (1)
1.
an electric railway operating below the surface of the ground (usually in a city);
- Example: "in Paris the subway system is called the `metro' and in London it is called the `tube' or the `underground'"[syn: metro, tube, underground, subway system, subway]
WordNet (r) 3.0 (2006):
subway system
n 1: an electric railway operating below the surface of the
ground (usually in a city); "in Paris the subway system is
called the `metro' and in London it is called the `tube' or
the `underground'" [syn: metro, tube, underground,
subway system, subway]